1.) Rn-222 decays from 400 grams to 6.25 grams in 240 minutes. How long is one “half-life.
1 answer:
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Answer:
665 ft
Explanation:
Let d be the distance from the person to the monument. Note that d is perpendicular to the monument and would make 2 triangles with the monuments, 1 up and 1 down.
The side length of the up right-triangle knowing the other side is d and the angle of elevation is 13 degrees is
Similarly, the side length of the down right-triangle knowing the other side is d and the angle of depression is 4 degrees
Since the 2 sides length above make up the 200 foot monument, their total length is
0.231d + 0.07d = 200
0.301 d = 200
d = 200 / 0.301 = 665 ft